Paleolithic Era旧石器时代
Dali Man大荔人

The site where archaeologists found the remains of Dali Man also contained stone chipped tools and animal fossils. The sediment layer covering the skull was dated as between 250,000 and younger than 350,000 years old using a stratigraphic profile technique by Yin Gongming, Zhao Hua, Yin Jinhui, and Lu Yanchou (2002). The authors are all geologists and focused on the strata rather than the surrounding fossil evidence. Dating material this old is problematic. Upheavals in the surface can shift or reverse strata. Landslides can mix older and earlier material. Sorting through core samples is an exacting task. Each year new techniques are developed that aid the investigation into our earliest history.